Post-weaning multisystemic wasting syndrome (PMWS) affects piglets post-weaning from 4 to 16 weeks of age (15-50 kg). Typically PMWS affects piglets one to two weeks after weaning and is very different from the wasting/poor weaner who fails to eat or drink adequately after weaning. PMWS piglets are weaners which have started to grow and then collapse quickly and often have an extremely poor response to antibiotics.
Porcine dermatitis and nephropathy syndrome (PDNS) affects pigs from 8 to 18 weeks of age and the most obvious signs are red-purple blotches on the skin, which become brown and crusted after a few days. Pigs are lethargic and may have swollen legs resulting from their nephropathy. This syndrome, also, responds poorly to antibiotics.
The causal agents of both PMWS and PDNS are at present unknown. The most likely suspect in both syndromes is a pig circovirus “type II” which is antigenically distinct from widely distributed normal non-pathogenic pig circovirus “type I”. Circovirus II (PCV II) has been identified on UK farms serologically. PDNS, which is thought to be an immune complex mediated disease, may also involve bacteria in its aetiology, though the part that they play is not clear.
PMWS is a problem which is recognised world-wide. PMWS was first reported in Canada in 1991, with reported incidents following in France (1995); USA (1996); Spain (1997); Austria, Denmark, Germany, Ireland, Italy, Netherlands and Northern Ireland (1998); Great Britain, Hungary, Japan, Korea, Portugal and Taiwan (1999); Poland (2000); Mexico (2001); and New Zealand (2003).
PDNS was first described in the UK in 1993 as a sporadic condition but since that time it has become increasingly associated with herds affected by PMWS, and has been reported all over the world.
With PMWS and PDNS the mortality rate is very high. The clinical characteristics of both PMWS and PDNS syndromes include an initial high fever (40-42° C.). Pigs with PMWS develop listlessness; very rapid wasting; development of a hairy coat and runted appearance. In addition, the lymph nodes may be palpable as they are grossly enlarged. With either syndrome, some pigs may also develop a slight cough and difficulty breathing.
To date, no effective treatments of or vaccines for PMWS or PDNS are available. As a general guide the following regimes have been used in order to attempt to combat both syndromes: changing of the herd to all-in or all-out protocols; age segregation; providing pigs with a good environment to limit effects of secondary infection; separating weaners that show signs of the disease to reduce the level of the disease in the pen; good gilt introduction protocols to ensure gilts are well acclimatised before entry into the main unit; and minimising cross-fostering.
These regimes, however, are limited in their effectiveness. An aim of the present invention is to more effectively protect against and/or treat and/or reduce the level of occurrence of both PMWS and/or PDNS.